Kits for manufacturing and assembling mold frames or bases typically include several pairs of plates which a craftsman stacks side-by-side on a workbench. Usually there are one or more pairs of plates that abut one another. During assembly, the abutting plates are held in alignment by dowel pins, which may be either hollow or solid that are received by aligned bores in the two plates. Assembly of the two plates can be difficult because the dowel pins may be driven completely into the first plate when the second plate is moved into engagement with the first plate. In addition, bores for the dowel pins, usually two in each plate, must be drilled through the two plates.
The practice has developed of constructing mold bases from square or rectangular plates of uniform face dimensions (i.e., width and height) and with bores in the four corners of the plates for receiving guide or leader pins that maintain the alignment of the plates. All of the guide or leader pin bores are in the same, predetermined location.
For ease of assembly, dowel pins are provided for aligning at least some of the plates used in the mold base. In some cases, dowel pin-receiving bores are machined in the plates for receiving the dowel pins. In other cases, the dowel pins are hollow to receive the leader pins and extend through aligned leader pin bores in several plates. The dowel pins often have a uniform outer diameter along their length, but there are some mold constructions in which the dowel pins have a larger outer diameter portion that is received in a pocket in one of the plates formed by counterboring the plate.
When assembling a mold base with the use of dowel pins, it is a common occurrence to accidentally push the dowel pin into a plate or series of plates due to a slight misalignment between two plates that are being assembled together. This problem can be avoided by using a dowel pin having a larger outer diameter portion which is lodged in counterbore of one of the plates. However, such dowel pins are relatively expensive to manufacture and an extra machining operation is required to form the counterbore.